One "Great BIG Ol Humongous" difference in Black & 7625 is;
You could load a 1/2oz of shot over a dram & a half of black & drop it in a 10ga shell & get essentially a .410 load out of it.
Try an equivalent load using 7625 & it wouldn't build enough pressure to Blow your Nose.
It takes a certain amount of heat & pressure to burn Smokeless efficiently & the slower it burns the more it takes to insure adequate burning. Slow powders are made slow by being treated with a "Retardant" so they don't burn so fast.
You keep shooting those slow powders under light loads at low pressures & one day you'll get a squib, "if-fen" your're lucky.
Its not unheard of that an improperly ignited load of powder can produce a "Secondary Explosion" which can take a bbl apart, about like an obstruction.
You've been warned, whether you want to believe it or not is strictly up to You.
